1. Field of the Invention
The present invention relates to a turbomolecular pump including a plurality of rotor and stator discs arranged alternatively one behind another and producing together a pumping effect, and a plurality of spacer rings for retaining the stator discs at a distance from each other.
2. Description of the Prior Art
The pump of the type discussed above has pumping active elements formed of rotor and stator discs provided with vanes and arranged alternatively one behind another. The rotor and stator discs generally are provided each with a support ring with vanes provided on the ring outer sides. The vanes, which are provided on the rotor discs rotate with a high speed and produce, together with the stator vanes, the pumping effect. The stator discs are retained at a distance from each other with spacer rings arranged at outer circumferences of the stator discs. The distance between separate stator discs is so selected that the rotor discs can rotate therebetween without contacting the same. The stator discs, together with the spacer rings, form the stator. The stator is centered by an inner wall of the pump housing. Such an assembly with stator discs, spacer rings, and a housing is disclosed in German Patent No. 3,722,164.
The drawback of the turbomolecular pump of the type disclosed in the German Patent consists in a large number of components which makes the construction of the pump rather complicated. Moreover, the pump has a rather rigid construction which makes the adaptation of the pump to the requirements of a particular usage rather difficult.
German Publication DE 19951954, which corresponds to U.S. Pat. No. 6,461,123, discloses a turbomolecular pump with a reduced number of components. In this turbomolecular pump, each stator disc, a respective spacer ring, and a section of the pump housing are formed as a one-piece part. However, a drawback of this construction consists in that additional parts are needed for securing and holding together separate stator components. The use of additional parts complicates the assembly of the turbomolecular pump and require additional space.
Accordingly, an object of the present invention is to provide a turbomolecular pump having a reduced number of components in comparison with known turbomolecular pumps.
Another object of the present invention is to provide a turbomolecular pump characterized by reduced manufacturing costs and a simplified assembly.
A further object of the present invention is to provide a turbomolecular pump that can be easily integrated into different systems and, thus, can be easily adapted to particular usage.